Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
  • C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
  • C23C22/364—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing also manganese cations
  • C23C22/365—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing also manganese cations containing also zinc and nickel cations
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
  • C23C22/08—Orthophosphates
  • C23C22/12—Orthophosphates containing zinc cations
  • C23C22/17—Orthophosphates containing zinc cations containing also organic acids
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
  • C23C22/08—Orthophosphates
  • C23C22/18—Orthophosphates containing manganese cations
  • C23C22/182—Orthophosphates containing manganese cations containing also zinc cations
  • C23C22/184—Orthophosphates containing manganese cations containing also zinc cations containing also nickel cations

Definitions

• This invention relates to compositions and processes for depositing zinc phos ⁇ phate containing conversion coatings on metal surfaces, particularly the surfaces of iron,
• the invention particularly relates to such compositions and processes that produce, at a high coating speed, a conversion coating with a very fine average crystal size.
• Statement of Related Art io The general process of zinc phosphate conversion coating is well known in the art. See, e.g., M. Hamacher, "Ecologically Safe Pretreatments of Metal Surfaces", Hen- kel-Referate 30 (1994), pp. 138 - 143, which, except to the extent that it may be contrary to any explicit statement herein, is hereby inco ⁇ orated herein by reference.
• con ⁇ tact of active metals with aqueous acidic compositions containing zinc and phosphate is ions results in the deposition on the active metal surfaces of a conversion coating con ⁇ taining zinc phosphate.
• the active metal is ferrous, iron phosphates are usually includ ⁇ ed in the coating, and in modern practice nickel and/or manganese are often included in the coating composition and thereby in the coating formed.
• accelerators include nitrate, nitrite, and chlorate ions, water soluble nitroaromatic organic compounds such as p-nitrobenzene sul ⁇ fonic acid, and hydroxylamine (the latter almost always in the form of salts or complex ⁇ es).
• One object of this invention is to provide a composition and process for phosphat- ing that will provide a protective conversion coating with a more refined crystal size than is now generally achieved by zinc phosphating.
• Another alternative or concurrent object is to provide a zinc phosphating composition and process that will form a high quality protective conversion coating during a brief contact time with a metal substrate to be coated, so that coil coating and other continuous phosphating operations can be run at higher speeds.
• Still another concurrent or alternative object is to avoid the formation of surface rust on small areas ofthe treated substrate that are blocked by gas bubbles from full contact with the conversion coating solution.
• a conversion coating forming aqueous liquid composition that comprises, preferably consists essentially of, or more preferably consists of, water and: (A) dissolved zinc cations;
• a dissolved component selected from the group consisting of organic acids and anions thereof that (i) contain at least two moieties per molecule that are selected from the group consisting of carboxyl and carboxylate moieties and hydroxyl moieties that are not part of a carboxyl moiety and (ii) do not contain more than
• M represents a hydrogen atom, a monovalent cation, or a monovalent frac ⁇ tion of a polyvalent cation; and, optionally, (E) a component of dissolved metal cations selected from the group consisting of metal cations, exclusive of zinc cations, with a charge of at least two;
• Various embodiments ofthe invention include working compositions for direct use in treating metals, make-up concentrates from which such working compositions can be prepared by dilution with water, replenisher concentrates suitable for maintaining op ⁇ timum performance of working compositions according to the invention, processes for o treating metals with a composition according to the invention, and extended processes including additional steps that are conventional per se, such as cleaning, activation with titanium phosphate sols (Jernstedt salts), rinsing, and subsequent painting or some similar overcoating process that puts into place an organic binder containing protective coating over the metal surface treated according to a narrower embodiment ofthe invention.
• Art- 5 icles of manufacture including surfaces treated according to a process of the invention are also within the scope ofthe invention. Description of Preferred Embodiments
• compositions according to the invention as defined above should be substantially free from many ingredients used o in compositions for similar purposes in the prior art.
• these compositions contain no more than 25, 15, 9, 5, 3, 1.0, 0.35, 0.10, 0.08, 0.04, 0.02, 0.01, 0.001, or 0.0002, percent of each of the following constituents: nitrite, chlorate, 5 chloride, bromide, iodide, organic compounds containing nitro groups, hexavalent chromium, manganese in a valence state of four or greater, ferricyanide; ferrocyanide; and pyrazole compounds.
• accelerator components such as those included in this list have no known detrimental effect (except for the danger of white specking zinciferous surfaces treated with compositions that contain too much 0 chloride, which is formed in situ from chlorate), but are generally not needed, and their absence may therefore be preferred for economic reasons.
• the dissolved zinc cations required for necessary component (A) may be obtained from any soluble zinc salt or from zinc metal itself or any zinc containing compound that reacts with aqueous acid to form dissolved zinc cations.
• Normally preferred sources are zinc oxide, zinc carbonate, and zinc dihydrogen phos ⁇ phate.
• the concentration of dissolved zinc cations preferably is at least, with increasing preference in the order given, 0.1, 0.2, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.85, 0.90, 0.95, 0.98, or 1.00 parts per thousand (hereinafter usually abbreviated as "ppt") and independently preferably is not more than, with increasing preference in the order given, 2.0, 1.8, 1.6, 1.4, 1.30, 1.20, 1.15, or 1.10 ppt.
• the dissolved phosphate ions that constitute necessary component (B) also may be obtained from a variety of sources as known in the general phosphate conversion coat ⁇ ing art.
• phosphate ion content will preferably be supplied by phos- 5 phoric acid added to the composition, and the stoichiometric equivalent as phosphate ions of all undissociated phosphoric acid and all its anionic ionization products in solution, along with the stoichiometric equivalent as phosphate ions of any dihydrogen phosphate, monohydrogen phosphate, or completely neutralized phosphate ions added to the compo ⁇ sition in salt form, are to be understood as forming part of component (B), irrespective o ofthe actual degree of ionization that exists in the composition.
• the concentration of component (B) preferably is at least, with increasing preference in the order given, 5, 6, 7, 8, 9, 10, 10.5, 11.0, 11.5, 11.9, 12.2, 12.4, 12.6, 12.8, 13.0, 13.2, 13.4, or 13.6 ppt -ind independently preferably is not more than, with increasing preference in the order 5 given, 100, 50, 40, 30, 27, 24, 21, 19, 18, 17, 16.5, 16.0, 15.5, 15.0, 14.5, 14.3, 14.1,
• the ratio ofthe concentration of compon ⁇ ent (A) to the concentration of component (B) in a conversion coating forming aqueous liquid composition according to the invention, whether working or concentrate, preferab- o ly is at least, with increasing preference in the order given, 1.0:50, 1.0:40, 1.0:35, 1.0:30,
• Component (C) is preferably derived from anions or other molecules each of which contains both at least one carboxyl(ate) moiety and one hydroxyl moiety that is not part of any carboxyl(ate) moiety, more preferably from the group consisting of citric acid, gluconic acid, and heptogluconic acid and the water soluble salts of all of these acids, most preferably from citric acid and its water soluble salts.
• concentration of component (C) in a working conversion coating forming aqueous liquid composition according to the invention preferably is at least, with increasing preference in the order given, 0.1, 0.2, 0.3, or 0.4 millimoles per kilogram of total composition
• mM/kg small crystal size of the conversion coating formed is desired, more preferably is at least, with increasing preference in the order given, 1.0, 1.2, or 1.6 mM/kg; if small crystal size ofthe conversion coating formed is desired and the concentration of component (D) is near the lower end of its preferred ranges as further described below, the concentration of component (C) in a working con ⁇ version coating forming aqueous liquid composition according to the invention still more preferably is at least 3.5 mM/kg.
• the concentration of component (C) in a working composition according to the invention preferably is not more than, with increasing preference in the order given, 50, 25, 15, 10, 7, 5, 4.5, or 4.1 mM/kg, and if larger crystal size is acceptable, more preferably is not greater than, with increasing preference in the order given, 3.2, 3.0, 2.8, 2.5, 2.2, 1.9. or 1.7 mM/kg.
• Component (D) preferably is selected from polymer molecules in which at least, with increasing preference in the order given, 60, 70, 75, 80, 85, 90, or 95 % ofthe mole- cule consists of one or more moieties with one ofthe formulas:
• OM OM more preferably the formula shown on the left, or in other words, acrylate rather than methacrylate moieties.
• at least 30, 50, 60, 70, or 80 number percent of these acrylate and methacrylate moieties in component (D) have hydrogen rather than any other atom or cation in the position in the formula indicated by the symbol "M" in the formulas shown.
• the weight average molecular weight ofthe polymers in the component (D), measured as its stoichiometric equivalent when all the acrylate and methacrylate moieties are in an acid form preferably is at least, with increasing preference in the order given, at least 400, 500, 600, 700, 750, 800, 850, 900, 950, or 975 and independently preferably is not more than, with increasing preference in the order given, 10,000, 9000, 8000, 7000, 6000, 5000, 4500, 4000, 3500, 3000, 2500, 2000, 1700, 1400, 1300, 1250, 1200, 1150, 1 100, or 1050. Also, independently ofthe other preferences for component
• the concentration of component (D) in a working conversion coating forming aque ⁇ ous liquid composition according to the invention preferably is at least 5, 10, 15, 20, 22, or 24 ppm and independently preferably is not more than 300, 200, 100, 85, 75, 65, or 55 ppm and, unless the concentration of component (C) is not more than 0.4 mM/kg, more preferably is not more than, with increasing preference in the order given, 45, 35,
• a working conversion coating forming aqueous liquid composition according to the invention preferably contains one or more metal ions selected from optional component (E).
• metal ions selected from optional component (E) are: Zn and Mn; Zn, Mn, and Co; Zn, Mn, and Cu; Zn and Cu; Zn, Co, and Cu; and Zn, Mn, and Ni.
• a working conversion coating forming aqueous liquid composition according to the invention contains, as at least part of optional component (E), dissolved divalent manganese cations in a concentration that preferably is at least, with increasing prefer ⁇ ence in the order given, 100, 200, 300, 400, 500, 550, 600, 650, 700, 750, 800, 825, or 835 ppm and independently preferably is, primarily for reasons of economy, not more than, with increasing preference in the order given, 4000, 3000, 2000, 1500, 1400, 1300, 1250, 1200, 1150, 1100, 1050, 1000, 950, or 900 ppm.
• optional component (E) dissolved divalent manganese cations in a concentration that preferably is at least, with increasing prefer ⁇ ence in the order given, 100, 200, 300, 400, 500, 550, 600, 650, 700, 750, 800, 825, or 835 ppm and independently preferably is, primarily for reasons of economy, not more than, with
• a working conversion coating forming aqueous liquid composition according to the invention is especially preferred for a working conversion coating forming aqueous liquid composition according to the invention to include, as at least part of optional component (E), dissolved divalent nickel cations in a concentration that pref ⁇ erably is at least, with increasing preference in the order given, 100, 200, 300, 400, 500, 550, 600, 650, 700, 750, 765, 785, or 790 ppm and independently preferably is, primarily for reasons of economy, not more than, with increasing preference in the order given, 4000, 3000, 2000, 1500, 1400, 1300, 1250, 1200, 1150, 1100, 1050, 1000, 950, 900, or 850 ppm.
• optional component (E) dissolved divalent nickel cations in a concentration that pref ⁇ erably is at least, with increasing preference in the order given, 100, 200, 300, 400, 500, 550, 600, 650, 700, 750, 765, 785
• the ratio ofthe concentration of zinc cations to the sum ofthe concentrations of manganese and nickel cations in a conversion coating forming aqueous liquid composition according to the invention preferably is at least, with increasing preference in the order given, 1.0:5.0, 1.0:4.0, 1.0:3.5, 1.0:3.0, 1.0:2.5, 1.0:2.3, 1.0:2.1 , 1.0: 1.9, 1.0: 1.7, or 1.0: 1.6 and independently preferably is not more than, with increasing preference in the order given, 1.0:0.2, 1.0:0.4, 1.0:0.6, 1.0:0.8, 1.0:1.0, 1.0:1.1, 1.0: 1.2, 1.0: 1.3, 1.0: 1.4, or 1.0: 1.5.
• the ratio of manganese to nickel preferably is at least, with increasing preference in the order given, 1.0:2.0, 1.0:1.7, 1.0:1.5, 1.0:1.3, 1.0:1.2, 1.0:1.1, or 1.0:1.0 and inde ⁇ pendently preferably is not more than, with increasing preference in the order given, 1.0:0.2, 1.0:0.5, 1.0:0.7, 1.0:0.8, or 1.0:0.9.
• a working conversion coating forming aqueous liquid composition according to the invention preferably includes, as at least part, and more preferably as all, of optional component (F) a dissolved source of hydroxylamine.
• the source may be hydroxylamine itself, but most users prefer to avoid potential hazards from handling pure hydroxylamne, so that a salt or complex of hydroxylamine is generally preferred.
• Hydroxylamine sul ⁇ fate which has the chemical formula (NH 3 OH) 2 SO 4 is particularly preferred for economy and lack of any ions that may be deleterious to the quality of conversion coating formed, e.g., chloride ions, which may induce white specking of any zinc-rich areas ofthe coated substrate.
• the concentration in a working conversion coating forming aqueous liquid composition according to the invention measured as its stoichiometric equivalent as pure hydroxylamine, preferably is at least, with increasing preference in the order given, 0.2, 0.5, 0.8, 1.0, 1.1 , 1.2, 1.3. 1.4, or 1.5 ppt and independ- ently preferably is not more than, with increasing preference in the order given, 5, 4, 3.5, 3.0, 2.5, 2.3, 2.1, 1.9, or 1.8 ppt.
• a working conversion coating forming aqueous liquid composition according to the invention preferably includes optional simple and/or complex fluoride anions component (G); more preferably, if the substrate surface includes a portion that contains at least 85 % of zinc, at least part ofthe fluoride present is in the form of fluo- boric, fluosilicic, fluotitanic, and/or fluozirconic acids and their salts, most preferably fluosilicic acid and/or fluosilicate ions.
• the preferable concentrations for fluoride in such a co - position are specified in terms of "active free fluoride", as measured by means of a fluor ⁇ ide sensitive electrode and associated instrumentation and methods that are described in U. S. Patents 3,350,284 and 3,619,300. Suitable apparatus and instructions for using it are commercially available under the name LINEGUARD® 101 A Meter from the Parker Amchem Division ("PAM”) of Henkel Co ⁇ ., Madison Heights, MI.
• PAM Parker Amchem Division
• the reading ofthe electrodes immersed in the sample is taken directly from the millivolt (hereinafter often abbreviated "mv” or “mV”) meter on the instrument and converted to ppm by comparison with the millivolt readings obtained with solutions of known free fluoride content, usually sodium or potassium fluoride solutions in water.
• mv millivolt
• mV millivolt
• the free fluoride content of a working conversion coating forming aqueous liquid composition according to the invention when a surface including areas that are at least 45 % aluminum is being treated, preferably is at least, with increasing preference in the order given, 100, 150, 200, 250, 300, 350, 375, or 400 ppm and independently preferably is not more than, with increasing preference in the order given, 1200, 1000, 900, 800, 750, 725, 700, 675, 650, 625, or 600 ppm. If a surface including areas that are at least
• the free fluoride content preferably is not more than, with increasing preference in the order given, 100, 75, 60, 45, 40, 35, 30, 25, 20, 15, or 10 ppm, but the total content of fluoborate, fluosili- cate, fluotitanate, and fluozirconate, which includes the stoichiometric equivalent as these ions of all corresponding acids and partially acidic salts added to the compositions, ir ⁇ respective ofthe actual degree of ionization existing in the composition, preferably is at least, with increasing preference in the order given, 0.1 , 0.3, 0.5, 0.7, 0.8, 0.9, 1.00, 1.10, 1.15, or 1.20 ppt and independently preferably is, primarily for reasons of economy and with increasing preference in the order given, not more than 3.0, 2.5, 2.0, 1.8, 1.6, 1.50, 1.45, 1.40, 1.35, or 1.30 ppt.
• the total amount of these complex fluoride anions is fluosilicate or its corresponding acid or acid salt.
• fluoride may be omitted altogether, and such omission is normally preferred for economic reasons. If any fluoride is present in the working compositions according to the invention for treating only ferrous substrates, the same preferences as noted above for the maximum amount of free fluoride activity in a composition for treating alumin ⁇ um-free zinciferous surfaces apply.
• the Total Acid and Free Acid contents ofthe composition are preferably measured and controlled.
• These acid contents consistent with general practice in the phosphating art, are expressed herein in "points", by which is meant the milliliters ("ml") of 0.1 NNaOH required to titrate a 10 ml aliquot sample, to a pH of 8.2 (e.g., with phe- nolphthalein indicator) for Total Acid and to a pH of 3.8 (e.g., with bromophenol blue indicator) for Free Acid.
• the content of Free Acid preferably is at least, with increasing prefer ⁇ ence in the order given, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0 points and inde- pendently preferably is not more than, with increasing preference in the order given, 3.0, 2.5. 2.0, 1.8, 1.7, 1.6, or 1.5 points; and, independently, the content of Total Acid prefer ⁇ ably is at least, with increasing preference in the order given, 15, 16, 17, 18, 19, 20, or 21 points and independently preferably is not more than, with increasing preference in the order given, 50, 40, 35, 32, 30, 29, or 28 points.
• the Free Acid and Total Acid con ⁇ tents can be adjusted into the preferred range, without disturbing the preferred values for other constituents of a conversion coating forming aqueous liquid composition according to the invention, by additions, to an otherwise satisfactory conversion coating forming aqueous liquid composition, of small amounts of strongly alkaline materials such as sodi- um and potassium hydroxides or strong acids such as nitric and sulfuric acids, as appro ⁇ priate for the direction in which it is desired to change the Free Acid and Total Acid con ⁇ tents, in a manner generally known to those skilled in the art.
• strongly alkaline materials such as sodi- um and potassium hydroxides or strong acids such as nitric and sulfuric acids
• make-up concentrate compositions are single package liquid concentrates, i.e., are aqueous liquids that consist of water and each of components (A) through (G), as recited above for working compositions, that are de ⁇ sired in the working compositions to be prepared from the make-up concentrate composi ⁇ tions, along with any other ingredients desired in the working compositions, except pos ⁇ sibly for strong acids or alkalies that are not part of any of components (A) through (G) and are added to working compositions after preparation thereof to slightly less than the final desired volume, in order to adjust the Free Acid and Total Acid contents therein as defined above.
• all the components except water of a make-up concentrate composition according to the invention are present therein in a concentration such that the ratio of the concentration of each component in the make-up concentrate composi ⁇ tion to the concentration ofthe same component in the working composition that it is de- sired to prepare from the concentrate composition will be at least, with increasing prefer ⁇ ence in the order given, 5:1.0, 10:1.0, 20:1.0, 30:1.0, 40:1.0, or 50:1.0.
• the concentrates are stable to storage in the temperature range from at least -20 to 50, or more preferably to 80, ° C. Stability may conveniently be evaluated by measuring the free acid and total acid contents as described above. If these values have not changed after storage by more than 10 % of their value before storage, the con ⁇ centrate is considered storage stable. With increasing preference in the order given, the concentrates according to the invention will be storage stable as thus defined after stor- age for 1, 3, 10, 30, 60, or 200 days.
• the actual conversion coating forming step in a process according to this invention preferably is performed at a temperature that is at least, with increasing preference in the order given, 35, 38, 41, 44, 46, or 48 °C and independently preferably is, primarily for reasons of economy, not more than 70, 65, 60, 55, 53, 51, or 50 °C.
• the time of contact between the metal surface being coated and a working composition according to the invention preferably is not greater than, with increasing preference in the order given, 200, 150, 120, 100, 80, 70, 60, 50, 40, 30, 25, 20, 17, 14, 11, 9.0, 7.0, 5.0, 4.0, 3.0, or 2.0 seconds, if a uniform and adequately protective coating is formed within that time.
• a process according to this invention is preferably operated under the conditions conventional in the art for compositions that are otherwise like the compositions according to this invention, except for substituting a conventional amount of nitrite accelerator for -ill ofthe hydroxylamine, acrylate and or methacrylate polymer, and at least difunctional acids and/or hydroxyacids described above for compositions according to this invention.
• the other steps preferably are conven ⁇ tional per se.
• the substrates were in the form of conventional rectangular test panels.
• Free fluoride contents preceded by the "less than” sign ( ⁇ ) were measured in the same way, but also mean that no hydrofluoric acid or other known source of uncomplexed fluoride was deliberately added; the free fluoride activity presum ⁇ ably arose from small concentrations of hydrofluoric acid known to exist in the fluosilicic acid that was deliberately added.
• the source ofthe acrylate polymer shown in Table 3 was AcusolTM 410 polymer solution in water, a product commercially supplied by Rohm & Haas Co.
• citrate concentrations in the working phosphating compositions and the resulting coating weights and crystal sizes are shown in Tables 4 - 1 1.

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• 1996
  • 1996-10-30 ZA ZA969146A patent/ZA969146B/xx unknown
  • 1996-10-31 AU AU74731/96A patent/AU7473196A/en not_active Abandoned
  • 1996-10-31 CN CN96198123A patent/CN1201495A/zh active Pending
  • 1996-10-31 BR BR9611356A patent/BR9611356A/pt not_active Application Discontinuation
  • 1996-10-31 JP JP09518203A patent/JP2000515586A/ja active Pending
  • 1996-10-31 WO PCT/US1996/017086 patent/WO1997017480A1/en active IP Right Grant
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  • 1996-10-31 EP EP96936939A patent/EP0866887A4/de not_active Withdrawn
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